A brand that cannot get a second order is not a brand yet. It is a customer acquisition cost with a website attached.
The uncomfortable version: most retention programs are built to harvest people who were going to reorder anyway. The work that matters happens with the customers who were not.
Where the money actually is
Move repeat rate a few points and the price you can afford to pay for a customer changes. That single change reopens acquisition channels that were previously unaffordable.